The patent document 1 describes a device that estimates a point (gazing point) gazed by a subject (or target person) and a personal parameter of the subject. The device obtains an image (eye image) including an image of an eyeball of the subject, estimates an eyeball attitude (that is, a direction of an optical axis of the eyeball), and estimates a direction (gazing direction) of a visual line of the subject from the eye image. The device quantifies a deviation amount between the optical axis direction of the eyeball and the visual line direction as a personal parameter.